The present invention relates to an automatic transmission system for vehicles, and more particularly to a system for controlling a vehicle transmission apparatus including a friction type clutch and a gear type transmission in accordance with the operation condition of the associated vehicle to perform an automatic gear-shift operation.
In general, the conventional automatic transmission system of the type described above uses map data for gear-shift control for determining a suitable gear position for the operation condition of the vehicle at each moment, and the operation for shifting the transmission to the determined suitable gear position is automatically performed (Japanese Patent Application Public Disclosure No. 59-151655 (151655/84)). Since the map data is adapted to determine the suitable gear position for the vehicle operation at that time on the basis of the amount of operation of the accelerator pedal and the vehicle speed, the transmission will be successively shifted up with increase in the vehicle speed when, for example, the driver fully depresses the accelerator pedal to accelerate the vehicle. In this case it follows that the clutch is disengaged at each operation for shifting-up while the vehicle is being accelerated. Accordingly, the driver from time to time experiences a feeling of deceleration in the course of the acceleration of the vehicle caused by his depression of the accelerator pedal, and this will cause incompatibility between what the driver expected in response to his operation and what he actually experienced.